This invention relates generally to sequencing valves for sequentially selectively coupling one of a plurality of outlet conduits with a single supply conduit that sequentially actuate in response to a change in fluid pressure and more particularly to an attachment for certain of said valves that provides for manual sequencing and also provides for locking said valve to a selected outlet conduit to prevent sequencing with pressure change.
Valves of this general type that provide neither manual selector nor locking are described in the following U.S. Pat. Nos. 3,524,470; 3,635,237; 3,924,652; 4,125,124; 4,083,290; 4,178,963; 4,195,665 and two that provide for manual selection, but not locking U.S. Pat. No. 3,459,208 to Clyde and U.S. Pat. No. 4,492,247 to Lockwood.
Valves of this type now in general use for lawn watering systems often use a single high presure water line to water a large area in zones. Each zone is fed by a branch water line from the valve. By feeding only one branch line at a time, a water supply line of limited pressure and volume can effectively water the entire area by watering one zone at a time. Such systems generally operate on timer mechanisms that periodically turn the water supply on and off with an electrically controlled valve or pump. The sequencing valves in common use are actuated by a pressure responsive reciprocating piston in the valve's flow path so as to sequence from one zone to the next zone when the water pressure is cut off and then on again. The on/off timing mechanism thereby provides both overall timing of the watering system and also sequencing, thus eliminating separate sequencing control mechanisms.
The valves of Clyde and Lockwood provide a part external to the valve housing that rotates in tandem with the inner valve mechanism. This provides indication of which outlet is selected even with the water supply off. It also provides a means to select an outlet manually with the water supply off, because moving the external device moves the internal selector. Unfortunately, this moving part is exposed to the elements and to trauma from which other parts are shielded by the valve housing. There are situations, especially during maintenance, when it is useful to manually select a particular outlet and also to lock the valve in that position so that it will not sequence when the water supply is turned on and off. However, that conveience should not be negated by exposing the internal valve mechanism to damage from an external moving part.